- Enable 'language' feature on unix targets.

The sdl version of the function 'SetLanguageIDs' is very limited, comparing to the win32 counterpart, as it will try to accept only the language codes (ie 'enu', 'fr', 'ptb', etc). If a different string is provided, zdoom will default its language to English.
Fix LZMA compilation on GCC with position-independent code (PIC) generation enabled

EBX register is used Global Offset Table in PIC
http://www.greyhat.ch/lab/downloads/pic.html
Merge branch 'language_sdl' of https://github.com/edward-san/zdoom